In the 1950s I spent a year as a graduate student in the Indiana University journalism department which was located in Ernie Pyle Hall, named for the great war correspondent killed by Japanese machine-gun fire in April 1945. The main auditorium was named after another Indiana alumnus murdered by the mobsters whose activities he was exposing in a small-town Ohio newspaper. I had gone into journalism partly as a result of being in thrall to American movies about men like this, romantic reporters ready to put their lives at risk for an important story. Twenty years later when I revisited Indiana I discovered that there had been a sudden increase in the enrolment of students in print journalism classes as a result of Woodward and Bernstein's exposure of Watergate and All the President's Men, the film celebrating their activities.

This all came back to me when seeing Veronica Guerin, a gripping thriller centring on the last two years in the life of the crusading Irish journalist on Dublin's Sunday Independent, who was murdered by gangsters in 1996. Heroic journalists are rare in British movies and indeed, since the almost simultaneous appearances of Performance and Get Carter 30 years ago, crime movies in this country have mostly been about colourful villains rather than those seeking to bring them to justice.

But then Veronica Guerin is not a British picture. Though shot entirely on location in Dublin and with an almost entirely Irish cast and crew, and some Irish money, it's a Hollywood production, directed by Joel Schumacher at his least mannered, produced with uncharacteristic restraint by the leading action movie producer, Jerry Bruckheimer, and scripted by two Irish Americans, Carol Doyle and Mary Agnes Donoghue. There are several classic scenes - such as the argument between the editor of the Sunday Independent and a bullying politician as the printing presses roll and roar behind them - that could have come out of any American newspaper movie of the past 70 years.

Sporting an impeccable Irish accent, the versatile Cate Blanchett plays Veronica, and the movie begins with her death on 26 June 1996, shot down in her red saloon car at traffic lights on the outskirts of Dublin by a leather-clad hit man riding pillion. She was talking to a police contact at the time. It's a shocking introduction, and we're equally chilled when the film returns to this moment in greater detail. An extended flashback has dealt with the courageous work that brought about her death - exposing the drug-dealers who were becoming rich while bringing misery to the slum kids of Dublin.

The film picks up shortly before John Boorman's The General (1998) ends. Also told in flashback from its subject's murder, Boorman's film - an altogether more complicated and sophisticated affair than Schumacher's - was a portrait of Ireland's most celebrated gangster, Martin Cahill. Early on in Veronica Guerin, Veronica is investigating the activities of Cahill when he and several of his henchmen are bumped off in various parts of the city in 1994.

People at the time attributed this to the IRA. Veronica, however, believes that this Chicago-style massacre was the work of major drug-dealers disposing of a dangerous, old-style competitor. So using her previous training as an accountant, she relentlessly pursues various suspects with the reluctant help of the police, who are fettered by antiquated laws. Eventually her investigation focuses on the career criminal John Gilligan (Gerard McSorley), who is laundering money all over Europe and establishing a legitimate front with a handsome equestrian centre in the countryside.

The movie cleverly establishes three worlds - the new underworld of fashionably dressed, Mercedes-driving criminals, the working-class north Dublin targeted by the drug dealers, and the cosy, prosperous middle-class exurban milieu of Veronica and her family. By challenging the first of these worlds on behalf of the second one, she is putting her own privileged existence in danger. A warning bullet through her study window is followed by a botched attempt on her life that leaves a bullet in her leg. Intrepidly she confronts the psychotically violent Gilligan in his lair and receives a ferocious physical and verbal beating.

Why does she take such risks when everyone around her counsels caution and withdrawal? A sense of justice and outrage, we infer, is combined with a lifelong competitiveness. A determination to excel in sport and at work arises perhaps from a particularly aggressive form of feminism that sprung up in Catholic countries such as Ireland and Italy. This is also expressed in her power dressing and in the reckless driving that often brought her before the courts. In addition, the film implies, she developed a contempt for the majority of her fellow journalists who steered clear of potentially dangerous controversy and viewed her as a grandstanding newcomer.

Cate Blanchett is a vital presence as Veronica and should have romantic teenagers lining up to get into journalism school. And she's well supported by Ciarán Hinds as the oily, self-satisfied crook who feeds her disinformation and Gerard McSorley as the terrifying Gilligan, while Brenda Fricker works wonders with the underwritten role of her mother. The film, however, is rather let down by an unduly triumphalist epilogue about the posthumous impact Veronica had on public opinion and the Irish criminal justice system.